lilcrypto/auth_poly1305.c

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/*
* Copyright (c) 2024 Lucas Gabriel Vuotto <lucas@lgv5.net>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdlib.h>
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#include "lilcrypto.h"
#include "auth.h"
#include "impl_poly1305.h"
#include "util.h"
static int
poly1305_init(void *arg, void *initparams)
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{
struct lc_poly1305_params *params = initparams;
struct poly1305_state *state = arg;
size_t i;
uint32_t t0, t1, t2, t3;
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state->h0 = 0;
state->h1 = 0;
state->h2 = 0;
state->h3 = 0;
state->h4 = 0;
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t0 = load32le(&params->key[0]);
t1 = load32le(&params->key[4]);
t2 = load32le(&params->key[8]);
t3 = load32le(&params->key[12]);
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state->r0 = t0 & 0x3ffffff;
state->r1 = ((t1 << 6) | (t0 >> 26)) & 0x3ffff03;
state->r2 = ((t2 << 12) | (t1 >> 20)) & 0x3ffc0ff;
state->r3 = ((t3 << 18) | (t2 >> 14)) & 0x3f03fff;
state->r4 = (t3 >> 8) & 0xfffff;
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state->x1 = 5 * state->r1;
state->x2 = 5 * state->r2;
state->x3 = 5 * state->r3;
state->x4 = 5 * state->r4;
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state->s0 = load32le(&params->key[16]);
state->s1 = load32le(&params->key[20]);
state->s2 = load32le(&params->key[24]);
state->s3 = load32le(&params->key[28]);
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state->blen = 0;
for (i = 0; i < LC_POLY1305_BLOCKLEN; i++)
state->b[i] = 0;
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return 1;
}
static int
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poly1305_update(void *arg, const uint8_t *in, size_t inlen)
{
struct poly1305_state *state = arg;
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size_t i;
for (i = 0; i + state->blen < LC_POLY1305_BLOCKLEN && i < inlen; i++)
state->b[i + state->blen] = in[i];
state->blen += i;
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in += i;
inlen -= i;
if (state->blen == LC_POLY1305_BLOCKLEN) {
poly1305_block(state, 1);
state->blen = 0;
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}
if (inlen == 0)
return 1;
while (inlen >= LC_POLY1305_BLOCKLEN) {
for (i = 0; i < LC_POLY1305_BLOCKLEN; i++)
state->b[i] = in[i];
poly1305_block(state, 1);
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in += LC_POLY1305_BLOCKLEN;
inlen -= LC_POLY1305_BLOCKLEN;
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}
for (i = 0; i < inlen; i++)
state->b[i] = in[i];
state->blen = inlen;
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return 1;
}
static int
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poly1305_final(void *arg, uint8_t *out, size_t *outlen)
{
struct poly1305_state *state = arg;
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uint32_t tag[POLY1305_TAGLEN_WORDS];
size_t i;
*outlen = LC_POLY1305_TAGLEN;
if (out == NULL)
return 1;
i = state->blen;
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if (i > 0) {
if (i < LC_POLY1305_BLOCKLEN) {
state->b[i++] = 1;
for (; i < LC_POLY1305_BLOCKLEN; i++)
state->b[i] = 0;
poly1305_block(state, 0);
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} else
poly1305_block(state, 1);
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}
poly1305_reduce(state, tag);
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store32le(&out[0], tag[0]);
store32le(&out[4], tag[1]);
store32le(&out[8], tag[2]);
store32le(&out[12], tag[3]);
lc_scrub(state, sizeof(*state));
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return 1;
}
static int
poly1305_auth(uint8_t *out, size_t *outlen, void *initparams,
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const uint8_t *in, size_t inlen)
{
struct poly1305_state state;
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if (out == NULL) {
*outlen = LC_POLY1305_TAGLEN;
return 1;
}
return poly1305_init(&state, initparams) &&
poly1305_update(&state, in, inlen) &&
poly1305_final(&state, out, outlen);
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}
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const struct lc_auth_impl *
lc_auth_impl_poly1305(void)
{
static struct lc_auth_impl poly1305_impl = {
.init = &poly1305_init,
.update = &poly1305_update,
.final = &poly1305_final,
.auth = &poly1305_auth,
.argsz = sizeof(struct poly1305_state),
.blocklen = LC_POLY1305_BLOCKLEN,
.taglen = LC_POLY1305_TAGLEN,
};
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return &poly1305_impl;
}